1. Field of the Invention
The field of the invention is that of electronic multiplexers for the transmission of digital data at high speed.
2. Description of the Prior Art
To minimize the number of digital data transmission cables, there is an interest in multiplexing the data so as to have one and the same cable carry several digital signals. To multiplex digital data, there are various types of techniques available. One of these techniques that is commonly employed is called TDM, standing for Time-Division Multiplexing. The principle of this technique is illustrated in FIG. 1 in the case of the transmission of two signals DI1 and DI2. The two digital signals having the same rate F are time-division multiplexed by a multiplexer M which transmits a single digital signal DM at a rate 2F over a single channel L, this signal DM is then demultiplexed by a demultiplexer DEM to restore the two initial signals DO1 and DO2 to the rate F. Generally, the multiplexed signal DM is obtained by interleaving the initial signals, every other bit of the multiplexed signal corresponding, for example, to the bits of the first signal DI1, the other bits of the multiplexed signal corresponding to those of the second signal DI2.
When the multiplexed signal DM is transmitted by optical pathways, the multiplexing means are either optical means or electronic means. In the first case, the term OTDM, standing for Optical Time-Division Multiplexing, is used. In the second case, the term ETDM, standing for Electrical Time-Division Multiplexing, is used.
The ETDM technologies are less expensive than the OTDM technologies which are normally reserved for very high speed transmissions. The ETDM technologies are currently limited to 80 gigabits per second. They normally use technologies:                For the lower rates, based on Silicon-(Bi)-CMOS, standing for Complementary Metal Oxide Semiconductor;        For the higher rates, based on SiGe, GaAs or InP.        
Currently, there is a growing need for transmissions at very high rates, greater than 80 Gbits/s, a rate that is not easily accessible to ETDM technologies.